add nextflow.config

[evanbiederstedt]

Moved parameters to nextflow.config.

Details of the code here: https://github.com/evanbiederstedt/clockwork/blob/feature/revise_NF_params/nextflow.config#L9-L16

Parameters I found here: https://github.com/evanbiederstedt/clockwork/blob/feature/revise_NF_params/nextflow.config#L18-L51

Note: It looks like all parameter names are the unique, except for max_forks:

It's 20 here:  https://github.com/iqbal-lab-org/clockwork/blob/master/nextflow/fake_remove_contam.nf#L5

Here it's 100:  https://github.com/iqbal-lab-org/clockwork/blob/master/nextflow/generic_pipeline.nf#L6 It may be best to rename the variable for one of these. 

Added default trace settings here, with fields I find useful: https://github.com/evanbiederstedt/clockwork/blob/feature/revise_NF_params/nextflow.config#L54-L58

Added default timeline, report, and DAG graphic. https://github.com/evanbiederstedt/clockwork/blob/feature/revise_NF_params/nextflow.config#L60-L73

You might want to remove the DAG graphic if your pipeline is stable---it will be the same thing after each pipeline run.

Also, you'll noticed I added shebangs to the NF scripts---feel free to remove if superfluous :)